Tesla Motors said its long-awaited $450 million loan from the federal government could come as soon as this summer, a crucial factor in its plans to build an electric-car factory in California.

“I am excited to report that the Department of Energy informed Tesla last week that they expect to disburse funds … within four or five months,” Elon Musk, Tesla’s chief executive and chairman, wrote in a newsletter distributed to customers Wednesday.

Tesla, based in San Carlos, stopped short of saying its loan application had been approved. Indeed, an Energy Department spokeswoman said Wednesday that her agency “has made no final decisions for specific applications for the auto-loan program.”

Still, Tesla is optimistic the department will approve its request for money from the $25 billion loan program to retool U.S. factories to make more fuel-efficient cars and trucks, said Diarmuid O’Connell, the company’s director of corporate development. Tesla has asked for $350 million to retrofit a factory to assemble its Model S electric sedan and $100 million for its battery-supply business.

“We have a high degree of confidence,” O’Connell said. For one thing, he said, Tesla has asked for a small amount compared with the Detroit Three automakers, which have requested $5 billion or more each.

Of the 75 companies that requested funds under the program, only 26, including Tesla, were told that their applications were “substantially complete,” he said.

Last week, Energy Secretary Steven Chu said the Obama administration would seek to speed up disbursements from the auto-loan programs, and suggested the funds would start flowing within two months.

Once planned for a green field off Highway 237 in North San Jose — and before that New Mexico — the Tesla factory now will likely end up in an existing building that can be retrofitted for electric-auto production. The company has said it’s looking at locations in both Northern and Southern California.

Once a site is selected, it will need to go through the usual regulatory and environmental-impact reviews. Tesla maintains that its Model S will go on sale in 2011.

Tesla has said it still might move its headquarters and research and engineering staffs to San Jose, but that’s uncertain.

The automaker currently sells the $109,000 Tesla Roadster, a two-seat electric vehicle. Musk said that the vehicle is sold out through November, and that it’s “highly likely” Tesla will become profitable by midyear.

The company has produced 200 Roadsters, and has more than 1,000 customers on its waiting list. That car is built at a Lotus factory in England.

Tesla will unveil a working prototype of its second car, the Model S sedan, on March 26 at Space Exploration Technologies, a rocket company Musk runs in Hawthorne. That’s where Tesla designer Franz von Holzhausen, an ex-Mazda stylist, has his office.

The Model S is expected to sell for about $60,000, although Musk said Wednesday that early buyers will get a $10,000 discount “as a gesture of gratitude.”

Tesla, which last year opened stores in Menlo Park and Los Angeles, will soon open showrooms in Chicago and London. New York, Miami, Seattle and Munich also will get Tesla dealership before year’s end, Musk said.